Wind Turbine Payback in Knox County, KY
Wind turbine payback in Knox County
No. The turbine wears out before it pays for itself.
At 30 m, the height a home turbine tower usually reaches, the wind in Knox County, KY averages 3.36 m/s (7.5 mph). A 10 kW turbine there would make about 3,794 kWh a year, worth $539 at KY's 14.2¢/kWh. Against an installed cost of about $100,000, that is a payback of over 100 years, and the turbine is built to last about 20.
What to do in Knox County
A home turbine is not worth buying for savings in Knox County unless your spot is far windier than the county average, 8.2 m/s at the hub against 3.36 m/s here. Per kW, solar panels would make about 1,232 kWh a year here against the turbine's 379, so get a solar quote first.
What would have to change
- Power would have to cost 132¢/kWh, 9.3 times what KY pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 3.36. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of KY
Knox County is the 2,665th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in KY is Fulton County at 5.54 m/s, payback 43 years.
Month by month in Knox County
March is the strongest month here, at 4.01 m/s and about 561 kWh. August is the weakest, 2.53 m/s and 120 kWh, so the best month makes 4.7 times the worst. November to March brings in 59% of the year's output in Knox County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.93 m/s | 527 kWh | $75 |
| February | 4.04 m/s | 520 kWh | $74 |
| March | 4.01 m/s | 561 kWh | $80 |
| April | 3.91 m/s | 504 kWh | $72 |
| May | 3.23 m/s | 282 kWh | $40 |
| June | 2.81 m/s | 170 kWh | $24 |
| July | 2.58 m/s | 129 kWh | $18 |
| August | 2.53 m/s | 120 kWh | $17 |
| September | 2.82 m/s | 173 kWh | $25 |
| October | 3.28 m/s | 299 kWh | $42 |
| November | 3.53 m/s | 365 kWh | $52 |
| December | 3.71 m/s | 441 kWh | $63 |
What a taller tower would buy
Measured at 10 m the wind in Knox County averages 2.14 m/s; at 50 m it is 4.14 m/s. That gives a shear exponent of 0.410, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 2,161 to 7,301 kWh a year, 238% more, before counting the extra cost of the taller tower. Why tower height decides it explains the shear behind these numbers.
| Hub height | Average wind | Output | Payback |
|---|---|---|---|
| 20 m | 2.84 m/s | 2,161 kWh | over 100 years |
| 30 m | 3.36 m/s | 3,785 kWh | over 100 years |
| 40 m | 3.78 m/s | 5,514 kWh | over 100 years |
| 50 m | 4.14 m/s | 7,301 kWh | 97 years |
Counties around Knox County
None of the 6 closest counties is windier than Knox County.
- Bell County, KY: 3.14 m/s, 3,034 kWh, payback over 100 years (15 mi)
- Whitley County, KY: 3.33 m/s, 3,684 kWh, payback over 100 years (18 mi)
- Clay County, KY: 3.36 m/s, 3,794 kWh, payback over 100 years (21 mi)
- Laurel County, KY: 3.33 m/s, 3,684 kWh, payback over 100 years (21 mi)
- Claiborne County, TN: 3.14 m/s, 3,034 kWh, payback over 100 years (29 mi)
- Leslie County, KY: 3.21 m/s, 3,265 kWh, payback over 100 years (29 mi)
Sun versus wind in Knox County
Knox County gets 4.22 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,232 kWh a year; one kW of the turbine above makes 379. Kilowatt for kilowatt, panels make 3.3 times as much here as the turbine. Panel output assumes an 80% system performance ratio. Wind or solar runs the same comparison for every county.
How this is worked out
Wind is NASA's Power climate record, the 2001-2025 average at 10 m and 50 m for the county's centre, carried to 30 m with this county's own measured wind shear and spread into hours with a Rayleigh distribution. The turbine is a generic 10 kW, 7 m rotor machine with 10% losses. Cost is $10,000 per kW installed with no tax credit, because the federal one ended in 2025. One county-centre number cannot see your hilltop or your tree line, so treat it as the starting point for a site survey, not a substitute. The full method and its weak spots are in how the numbers are made.